The present invention relates to a semiconductor device, and particularly to a technology effective if applied to a semiconductor device used in mobile communication equipment such as a cellular phone.
A configuration of a power amplifier for amplifying a transmit signal has been described in Japanese Unexamined Patent Publication No. 2008-135822 (patent document 1). The power amplifier described in the patent document 1 has two amplifying paths for transferring transmit signals having a phase difference of 90° with respect to each other. Namely, the power amplifier described in the patent document 1 is of a power amplifier which amplifies transmit signals having a phase difference of 90° respectively, and thereafter combines respective power of the transmit signals by means of a power coupler and outputs the same. A so-called configuration of balance amplifier has been described therein.